737 MAX Flight Crew Operations Manual
Fire Protection -
System Description
8.20.6
MN-FLT-OH-201
After the initial indication of a cargo compartment fire, the FWD/AFT cargo fire
warning light(s) can extinguish, remain illuminated, or re-illuminate over the
remainder of the flight. If the FWD/AFT cargo fire warning light(s) re-illuminate,
both master FIRE WARN lights also re-illuminate and the fire warning bell
sounds.
Cargo Compartment Fire Suppression
The Cargo Compartment Fire Suppression system provides fire suppression to the
forward and aft cargo compartments using a shared system of fire suppressing
chemical agent. Either the forward or aft cargo compartment can be selected for
discharge of the fire-suppression agent. Compartment selection is made by
pushing the appropriate cargo fire ARMED switch, which arms the discharge port
for the selected compartment. Once armed, the system is activated by pushing the
cargo fire DISCH switch. The cargo fire DISCH light illuminates once the bottle
contents are discharged. It may take up to 30 seconds for the light to illuminate.
The system suppresses fire, and might not be capable of completely extinguishing
a fire. Smoke can remain or continue to be generated within the cargo
compartment until the fire is extinguished by firefighting personnel upon landing.
The optical sensors of the Cargo Fire Detection System cannot distinguish
between smoke particles and the fire suppression agent. The cargo compartment
fire warning lights may remain illuminated or re-illuminate after discharge of the
fire suppression bottles.
1B401, 1B402, 1B801 - 1J594
Two Halon-filled fire-suppression bottles are installed: one 25 lb High-Rate
Discharge (HRD) bottle and one 33 lb Low-Rate Discharge (LRD) bottle. After
the appropriate cargo fire ARMED switch is pushed, pushing the cargo fire
DISCH switch completely discharges the HRD bottle contents into the selected
cargo compartment and starts a 15 minute timer. After 15 minutes, the LRD bottle
discharges its contents at a reduced metered flow into the selected compartment.
This provides 195 minutes of fire suppression, supporting a 180 minute flight and
a 15 minute reserve. Discharge of the LRD bottle may be disabled if the system is
disarmed. Upon landing, if the HRD bottle was discharged and the system
remains armed, the LRD bottle discharge is inhibited.
March 1, 2021
